FIELD OF THE INVENTION
This invention relates to an improved process for producing dicumylperoxide.
Hithertofore, there have been known processes for producing dicumylperoxide (hereinafter refered to as DCP), in which cumene hydroperoxide (hereinafter refered to as CHP) and .alpha.,.alpha.-dimethylbenzyl alcohol (hereinafter refered to as .alpha.-CA) are reacted. These processes are as follows: (1) A process characterized in that a strong acid such as sulfuric acid, perchloric acid, p-toluenesulfonic acid, a cation exchange resin, or the like is used as the catalyst in a reaction system (Japanese Patent Publication Nos. 10668/1962 and 2265/1963, U.S. Pat. No. 2,668,180 and British Pat. No. 792,558); (2) A process characterised in that the reaction is carried out using a lesser amount of the strong acid catalyst, while removing the water which formed in the reaction system therefrom under reduced pressure (Japanese Patent Publication No. 16719/1962); (3) A process characterized in that an oxalic anhydride is used for the reaction as the acid catalyst and a dehydrating agent (Japanese Patent Publication No. 27240/1964); (4) A process characterized in that potassium bisulfate or the like, which is a weak acid, instead of the above stated strong acid catalyst, is used for the reaction, while introducing an inactive gas in the reaction system (Japanese Patent Publication No. 12374/1960).
However, ranges of the optimum usage amount of the catalyst and of the reaction temperature in the process (1) are narrow because CHP and DCP are easily decomposed by the strong acid, and the process gives a low yield under the usual reaction conditions.
The process (2), in which the range of optimum usage amount of sulfuric acid is also narrow, needs a complex installation in order to carefully maintain the optimum reaction temperature and the reaction pressure while removing the water formed in the reaction system from the reaction system by distillation.
The process (3) involves the possibility of decomposition of DCP. because anhydrous oxalic acid is a strong acid and further is used in a large amount.
For these reasons there is a drawback in that the reaction should be carried out for a long time, while maintaining the reaction temperature at about 40.degree. C.
In addition, oxalic acid is strongly poisonous and exerts large corrosion activity on metals.
For the process (4), for which the reaction rate is slow, it is necessary to raise the reaction temperature up to about 90.degree. C.
It is not preferable to obtain a peroxide, which is apt to undergo thermal decomposition at such a high temperature.
Especially, it is dangerous to produce the peroxide in an industrial scale production according to the process (4), because the resulting peroxide is kept at such a high temperature as stated above, with the result being that an abnormal reaction happens in the reaction system and cause an explosion.
As mentioned above, the conventional processes for producing DCP by the reaction of CHP and .alpha.-CA are either one in which the reaction is carried out under strict restrictions using a strongly acidic catalyst or ones in which the reaction is carried out at a high temperature using a weak acid catalyst.
Neither process is preferable as an industrial scale production process in view of the yield and safety.